Recently, in the field of endoscopes, a capsule endoscope equipped with an imaging function and a radio communication function emerges. The capsule endoscope is swallowed from a mouth of an examinee, which is a subject (human body), for observation (examination) and is naturally discharged from the organism of the subject later. During this observation period, the capsule endoscope moves through the inside of internal organs (the inside of a body cavity) such as a stomach, and a small intestine following the peristaltic activity of the organs, and sequentially images the internal organs using its imaging function.
In the observation period during which the capsule endoscope moves through the internal organs, image data imaged in the body cavity by the capsule endoscope is sequentially transmitted to outside the subject by a radio communication function such as Bluetooth. The image data is accumulated in a memory provided in an external receiving device. The examinee carries the receiving device having a radio communication function and a memory function so as to freely move without experiencing any inconvenience even in the observation period after swallowing the capsule endoscope until naturally discharging the same. After the observation, a doctor or a nurse displays the image imaged in the body cavity on a display unit such as a display to perform a diagnosis based on the image data accumulated in the memory of the receiving device.
Generally, the receiving device includes a plurality of antenna elements that receive an image signal transmitted from the capsule endoscope, and the plurality of antenna elements are dispersedly arranged on the exterior of the subject. The receiving device switches and selects an antenna element with few reception errors of the image signal for reception of the image signal. Patent Document 1 describes a receiver in which antenna elements each having an adhesive adhere to a predetermined region on the subject so that the antenna elements are arranged on the exterior of the subject, and receptions of the plurality of antennas are switched, whereby a location of an in-vivo capsule endoscope, which is a transmission source of an image signal, is detected based on an electric-field strength received by each antenna element. Generally, the antenna element includes an antenna main body, and a coaxial cable that adheres to the antenna main body so as to be electrically connected thereto.
Patent Document 1: Japanese Patent Application Laid-open No. 2003-19111